Many modern wireless handheld communications devices, whether cellular telephone handsets or personal digital assistants (PDAs) are equipped with ancillary features.
One such feature that is gaining popularity is a GPS receiver whereby the present location of the handset of the PDA may be established to within a precision of a few to a few hundred feet and by which a precise map of the immediate vicinity and/or directions from such present location to a desired destination may be provided.
Such GPS receiver circuits typically make use of a fixed, free running crystal oscillator (XO) or temperature compensated crystal oscillator (TCXO) to generate a local clock to control its operation and to permit synchronization with a plurality of geosynchronous satellites forming part of the Global Positioning System (GPS).
Typically, wireless handheld communications devices also employ a crystal oscillator to clock and control the cellular radio circuitry and to permit communications with a cellular base station.
Accordingly, as board space and component cost of such devices is generally at a premium, it is desirable to provide a novel and improved circuit and method for implementing a plurality of clock circuits from a common crystal oscillator.
It is further desirable to provide a multiple clock circuit that has a reduced component count and board footprint.
It is still further desirable to provide a multiple clock event from a common crystal oscillator that may be used in a navigation satellite receiver, which is relatively impervious to adjustments to a voltage control input of the oscillator.